A project of Volunt::.ers in Asia
The Use of Wheelbarrows in Civil Construupn
World Bank Technical Memorandum NC. 13, 1975
Published by:
The World Bank
Transportation and Urban Projects Department
1818 H Street : V.
Washington. ;L ,::*
433 USA
;~v:i.latJ from:
:V rid Bank
Iiandportation and Urban Projects Department
1818 H Street, N.W.
Washington, DC 20433 USA
"hi:
Reproduced by permission of the Publications
Department, the World Bank.
Reproduction of this microfiche document in any
form is subject to the same restrictions as those
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Yhi.spaper is for stafr'use. The
views expressed are those of the
authors and not necessarily those
of the Wmld Bank.
WORis RUK
STUDY OF TRE SE3STITU!CION
OF LAROR -4RDEQUIPMERE IN CIVIL CONSTRUCTION
lechnioal MemorandsnrNo. 13
The Use of Wheelza?-v7s in Civil Construotion
Octobo? 1975'
Thie ~randnm
describes the ,4-u terietice of wheelbarrows,
the me&mn.ios of their ueo, VLX-:I.G.-'
-rs,pdcrte
of their design and
featurea of wheelbarrow working, all with partiou:!arreference
to the task of haulage in civil con;;truction.In addition,
relationahips for estimating produotivity using wheelbarrows are
presented, based on a simple theoretical work cycle 'calibrated'
using the results of production studies currently available.
An earlier memorandum in this series (Xo. 1) dealt with some
(limited) experiments with wheelbarrows. This memorandum describes
new work wbish is aomplementary to those dperimewb.
T,&nsport Research Division
Transportationand Urban Projects Department
/.
\1 1
Preface
Thi. J , one cf a series of papers prepared in the course
of the %-h&y of the Substitution of Labor and Equipment in Civil
Canstruotion. The paper is prepared with the objective of generating discussion on the results of the stx;u,Q
as and 4x11 they are
therefore,must be
available. The conclusions of this pap,:.:,
considered tentative end subject to ? vS.::.;r
in the light of further
field work and analysis. It is hoped c:-*tengineers will find
‘these results useful in plaming and exew,LLag labor-intensive
civil constmotion projects. Comments ace solicited from all
interestedpersons.
The paper is based on the field work LL India and
Indonesia undertaken by Scott Wilson Kirkpatrick & Partners
(Consultants)in collaboration with the Governments of India and
Indonesia; M J Sharrock carried out the analysis under the overc11 direction of P A Green. 411 the week in the study is supervised
by Inder K.Sud of the World Bank. Financial support for the study
is being provided by the World Bank and the Governments of Canada,
Denmark, Federal Republic of Germany, Finland, Japan, Norway,
Sweden, United K%ngdom and the United States.
(ii)
C0nten.t;
I.
~J-J~~W~Tg
II.
-0W
CBAR&XZXSTZCS
III.
wHlm&umow
MElcHANIcs
Y4.e
m
2?ollingP~siatame
Relation betme:~ Load and Gradient
Optimum Wheelbazmw Load
IV.
la3J3E!LBABRow
rnSIGiJ
Whmls and Tires
015 or Two Wheels, Western or
CfhinesePattern
berings
Bef
FZXIUs
V.
~WWORKiZNG
8
9
9
9
11
Western-Style Wheelbarrows
Chinese Wheelbarrows
11
13
VI.
FRODIJCTFIITYOF wHEEI;BBRROWS
14
VII.
COST OF -0W
17
VIII.
iZSClJ8SION
Figures:
1
HAULBEE
19
WESTERN-STYLE BARROW DEVELOFED FOR STUDIES OF LOW B
CONSTRUCTION IN INDIA. (photograph.)
2 WESTERN-m
E&MOW, IIOCALLYAVAILA~~I,?~
IN INDONEXA,USELD 1A
CANAL CONSTRUCTION SmnS.
(photograph)
3 HAULAGE ON U!FGHADEUSING WESTERN-STYLE BARRUW ANIlTIMBER BARROW
RUN. (photograph)
PREVXNTION WXfKS IN NO4 C~SEWHEELBARROWINUSEONFLOOD
CHINA.
REZATION BEXVEBN KAXD!KM BWWEIGEiT
AK0
5 Cm
GFLKMZNT.
6 MEEUMRROW HAULAGE : PROlXJCTIVITY/HASJL
LENGTH RELATIONSHIP.
HAJJI,
LENGTHS
7 UNIT COST OF WHEEiXd.RROWHMliXGEFORD~
CCMPAEZDWITH SIIQLARlXFdIBA~~ HAULAGE.
-1I.
~X~'?LCDUCTION
In earlier times irlwestern countries wheelbarrows were
I.
a common mode of mass haulage in labor-intensivecivil construction. Indeed, the so called 'navvy' barrow for general light
haulage purpc~~s is still veq much in evidence on small construction contracts. In China, where the wheelbarrow probably originated,
it has long been widely used for earthworks haulage, although in
a form and method of use distinctly different from the &EUopean
pattern. Ry contrast, in India and Indonesia (and probabiy other
parts of the world aloo) the wheelbarrow does not appear ever to
have come into common use. Hence it has often been suggesttxithat
productivity of labor in India end eisewnere could be improved by
the introduction of wheelbarrows because, while they.are iass
versatile than tradiii;ional
load carry.inghauLage methods .suchas
the headbasket, they enable a worker to move a load msny times as
.
great as a typicei basket load,
During the present study, experftlental
investigations
2.
have been made of wheelbarrow haulage in earthworks. Construction
of road end canal embankments has also been carried out using
either specially designed or locally avaU.able wheelbarrows of
western style. This progrsm of work is oontinuing,using both
weetezzland ohinese wheelbarrows,but on the evidence available
at preeent it is possible to give some indications about the
usefulness of wheelbarrows for haulage in civil construction and
about the productivity that can be expected using western-tyle
wheelbarrows. In addition, the appropriate circumstances and
methods of wcrking can be suggested end some of the limitations
of using wheelbarrows can be described.
II.
WHE23I;amOW CXM.ACTELRISTICS
Traditionally, wheelbarrows have been provided with a
3.
single wheel. Two-wheel barrows and small carts are not uncommon,
but these are generally most suitable for handling materials in an
industrial or similar environment where smooth paved surfaces are
common. The singleeheel layout is to be preferred for the rough
surfaces encountered in earth-dorksowing to its better manoeuvrability and greater ease of avoi .
or overcoming obstacles.
1 has to be provided, the need
Furthermore, where a barrow run"r?
to provide only a single narrow track is a considerable advantage
in favor of the single-wheel layout. Although a two-wheel barrow
has better lateral stability for a given load, the balance of
advantages definitely seems to lie with the single wheel, which
also can be unloaded more quickly and easily than the two-wheel
variety.
Western-e le barrows have a struck capacity in the
4.
7 ,and this has usually been found daing the
region 0.06 to O.OBm
study to allow a satisfactory payload of loose soil. A strongly
made barrow of this size can weigh 40 to 50 kg. For earthworks
containing rocks or boulders, this weight may be necessary, but
for ordinary soil EClighter type of barrow construction weighing
20 to 30 kg is usually adequate. Extra light-weightbarrowe of
10 to 15 kg have been found to be rather short-lived,but aould be
uued in special circumstances and on the basis of regular renewal
of a replaceable body. The larsest wheel which can be usefully
accommodated is 40 cm diameter and a pneumatic tire snd sealed
ball bearings are probably economically justifiable d&spite the
high initial co&.
Handle width and height must be tailored to
the stature of the workforce, so as to give a fairly upright
stance, with straightened arms and back,
The modern Chinese earthmoving wheeibarrow has a large5.
diameter pneumatic-tired wheel of spoked construction. The
capacity is around double that of the western type, and the load
is carried on a flat platform placed above the wheel. QI other
than slight gradients, assistance is profded by pulling on ropes
attached to the barrow. The increased weight on the handles and
greater balancing problem, coapared with Ike wesTern barrow, are
countered by the use of Q stra? fixed to the herties and passing
over the hauler's shoulders.
(‘1
A barrow run is a specia5y smooth strL> on which the wheel
of the barrow can rur,; or'zafi
it is a line of <inbeG planks laid
end to end (see i?ig.1).
-;-
Various wheelbarr?!,;':
:.r:
use fcr eart~oCx.g are shown
6.
Other wheeibarrows have been ill-ztrated in
inFigs.l-4.
Technical Memorandum No. 1 of this series.
,
-a-
The following considerations investigate in a general
7.
way some of the physical constraints on wheelbarrow performance
and design. h the abbeIG3 Of SpOCiSi f&UdieS t0 determine exact
values of parameters, quantities derived must be regarded as
approximate. Eowever, the results are confirmed in part at least
by experimentalobservations made in the course of the present
Study.
Roiling Resistance
When a body rolls on a surface the force resisting the
8.
motion is termed rolling friction. This has a different valu
from that of ordinary sliding friction. A simple expression t2 >
used in mechanical engineering for rolling friction, applicable
to fairly hard elastic materials, is:
Rolling Resistance Force =
Weiaht of Body x Rolling Friction Coefficient
Iiadiuaof Wheel
!l?his
expression indicates that, other factors remaining constant,
the rollvlg resistance is inversely proportional to the diameter
of the wheel. Therefore, in seeking to minimise rolling resistance the aim should be to use as large a wheel diameter as
possible. The coefficient in the above expression has dimensions
of length, it varies with the conditions, but is mainly controlled
by the nature of the materials in contact. For examples, with an
iron wheel on sn iron rail the value of the coefficient may be
assumed to be 0.5 nm~,with an iron wheel on asphalt 4 mm, and with
an irm .,:heel
on a wooden plank 6 mm. These figures are approximations, since various investigators are not in close agreement on
the 'true' values for rolling friction coefficients.
Considering next pneumatic tires, the situation is more
complex, as rolling resistance can arise from two different sources.
When operate over'hard surfaces, resistance is mainly due to
energy absorbed in the flexing of the tire as it rolls; whilst
on soft ground a large amount of work may be done in the defonnation of the soil by the wheei. In tine former case high inflation
pressure reduces resistance, in the latter case, low inflation
pressure can minimise the energy losses due to soil disturbance
and hence reduce rolling resistance. It is evident that wheel
diameter, tire pressure and soil characteristicsail influence
4.
(2)
See Bdninery~ s Ra.C~ook 1974
the roiling resistance, and as yex no simgle tlheoryhas been developed
to predict roliing resistance or'pneumatic tires on soii. Ill
civil engineering calculations for earthmoving, an all+mbracing
assessment of rolling resistance is used. This is sometimes
referred to as the Rolling Resistance Factor, end Magibe expressed
per tonne or as a decimal fraction of total.load. Not
aa
surprisingly,various texts of reference list markedly differing
values for this factor, so that it is usually difficult to select
representativevalues. However, together with the data on iron
wheels quoted above, the values of rolling resistance factor given
in Table 1 are probably appropriate in the context of wheelbarrows
and similar light haul&&y.
Table 1: Typical values for rolling resistance factor.
fraction of total
30 cm dism. iron wheel
40 cm diam. pneumatic wheel
~$0cm dism. iron wheel
30 cm diam. iron wheel
40 cm diam. pneumatic wheel
smooth hard e
Relation between Load and Gradient
The continuous force which can be exerted manually to
10.
push a wheelbarrow is about 15 kg. To obtain a precise knowledge
of this force would require sophisticated experiments and study of
a range of jndividual workers under various conditions. However,
a precise knowledge is not necessary in the following reasoning,
and the figure of 15 kg (obtained in simple tests using a spring
balance attached to an empty barrow) is sufficiently ace-urateto
give some useful indication of the relation between load and
gradient for wheelbarrow hzzlage.
Assuming that the wheelbarrow is running on a good
11.
surface and with a factor of rolling resistance equal to 0.05
(see Table l)$ the maximum gradient which can be negotiated with
various all-up weightE (W) is shown in Table 2.
-6-
Table 2:
Typical msximum gradients which can be negotiated by
wheelbarrows having different all-up weight. (Assumes
pushing force of 15 kg and rolling resistance factor
of 0.05).
Further calculations are shown graphically in Fig. 5 for three
different running surfaces, viz. a hard smooth surface, poorly
maintained earth, and loose sand and gravel,
These oalculatione are necesbarily of an ill
ra%ve
12.
vi
nature only, but experimental
work
.~
- previously reported 3 does
_ -providea 'spot' confirmation. In these experiments a gross load
of 170 kg at 496 gradient was found to be too great a load on a
hard e5rth running surface, whilst 4z&g gross load could be handled
con%zxusly, albeit at a somewhat Ad\ stied
speed. Thirjis seen on
Fig. 5 to Pzee quite well with the theoreticalprediction developed
above. IInpassing, it msy be noted that this calculation indicates
that at ,>bout10% grade and on the best surface considered only about
two headbezket loads (i.e. 60-70 kg) oan be moved.
Ootimum Wheelbarrow Load
The ar@ment above can be a basis for deter&ning the
13.
optimum wheelbarrow load under various conditions. The most
important of the operating conditions is clearly the running surface.
It is suggested that it will normally prove economic to provide
a good haul route condition, since the load which may be moved is
seriously limited by a poor working surfaoe (unlike humsn or
snimal load-carryingmodes of haulage).
(31 See Technical Memorandum No.
1
of this series.
‘i -
To date iz the study', wheelbarrow haulage has been
14.
employed on work where individual haulers have moved their own
loads without any external assistance. This is the most obviously
suitable mode of working on linear sites. However, on compact
sites, it is thought that assistance on steep slopes rmght be an
economical solution, when winching, towing, or other means might
be provided to help the movement of the wheelbarrow and effectively
increase the load which could be handled. This could involve a
semi-permanezt
installation at points where haul routes traversed
inclines. In these circumstances the prinzzryfactor governing
maximum load would be the rolling resistance on level ground, and
it is suggested that 200 to 250 kg wculd probably be about the
correct all-up weight to aim for, on the basis of Fig. 5. This
would correspond to a pay load of say 150 to 200 kg. For the case
of fully independent h-iulers,a much lower load will normally be
appropriate, since the great majority of earthworks involves at
least some haulage on rising gra,des. Taking for exsmple low
embankment construction as a typical case9 a rise of 2-3 meters
often occurs in a haul length of say 50 to 60 meters; as an
overall gradient this is equivalent to 3 to 6%. IIIpractice a
combination of level haul and short ramps would occur in this
task, but assuming that the overall grade is of relevance, an
d1-p
Wei&it of '120 to 170 kg xmld be the predicted maximum.
This would allow a payload of 90 to 120 kg.
IT.
W=K?DLBrwxOWIJESIGN
In seeking an efficient wheelbarrow design It must be
15.
recognised that no single solution can be put fr,rwardas an ideal,
since the circumstances of particular wheelbarrow applications lead
to conflicting requirements. Most wheelbarrows will in practice be
used under a variety of conditions and therefore a compromise must
be achieved w 'ch will best meet the most frequently prevailing
conditions (4?? The factors which have been noted affecting size,
geometw, construction, etc., as they apply to the main compounds
of the barrow, are discussed below.
Wheels and Tires
The primacy factor influencing the choice of wheel and
16.
tire is the running surface on which the barrow is used. On rough
uneven surfaces a large diameter wheel overcomes small obstacles
more easily than a small wheel and encounters less resistance. The
ssme can be said of pneumatic tires in comparison with solid tires.
On a smooth paved surface by contrast the advantage of a large
wheel is no longer really significant, and any hard tire will give
a relatively low rolling resistance. Pneumatic tires are more
costly than solid tires, but can have an equal or hi&er resistance
to wear, and are lighter, thus increasing the possible payload.
One or Two Wheels, Western or Chinese Pattern
Sn the case of one-wheel western style barrows, the wheel
17.
diameter cannot be much greater than 40 cm without causing the aLle
to become too far from the center of gravity of the load, thus
transferring an undesirable proportion of the load to the handles.
At the same time, the height of the center of gravity rises as the
wheel diameter is inoreased, and this produces an increasingly
unstable situation as the balance of the barrow worsens msking any
tendency to topple difficult to control. On the large wheel,
Chinese-patternwheelbarrow the high load center and resulting
balance problem are offset by the use of a shoulder strap, but this
will tend to lengthen the processes of taking up the load and of
UlilO5diDg. This factor, together with greater load capacity, would
probably increase the optimum haul length for use of the Chinese
barrow in compsrison with the western pattern. More difficulty
is aIs0 experienced in unloading two-wheel barrows compared
(4) However, details have been given in Technical Memorandusso. 1 of a robust, single-wheel, western-style barrow (Type G) which
appears to be well suited to haulage in civil construction; although
it must be stresse,?.
that its proportions may not be ideal for all
types of p!!sique.
-3-
-CA the single-wheel sreoka‘.npattern, asr! two
wheels give very poor manoeuv:atility, except 0.1smoot,.even
,,4n;
surfaces. This effectively L-:.-Sit out for use on rough '4.:
however, for une on paved areas thp two-wheel iayout is very.
heavy loads of concrete, aggregate 9 asphalt
suitable for scrying
over longer c.~stances.
Bearings
A good plain bearing when neu, and with lubrication, is
18.
not much inferior to a ball besring as far as friction is concerned,
and m&es only a small contribution to rolling resistsnce compared
with the contribution due to the tire. However, one of the
principle causes of the shor: life of barrows freq?.ntly observed in
practice is excessive T.rear
of plati besrings, and &or this reason
sealed ball bearings appear to have a definite advantage despite
their relatively high cost. They are generally maintenance free and
subject to practically no wear.
Ideally the size of the body should be a function of the
19.
load to be csrriec'and the nature and.density of the material being
transported. For a typical payload of 100 kg (see para. 14) yd
when carrying loose dry soil, a capacity of approximately~O.lm is
required, whiist with wet concrete a capacity of O.O$ would suffice.
Some compromise is possible, as a body of intermediate size can be
heaped up with soil or partially filled to avoid spillage when
carrying concrets. The body shape should be shallow to give a low
center of gravity, with sloping sides for ease of emptying in the
case of single-wheel barrows, when too it should be deeper at the
front to place the load olose to the wheel. Bodies should be replaceable, since this psrt of the wheelbarrow is subject to the most wear
and if made of metal sufficiently thick to resist all normal damage
would be uneconomically heavy and expensive. The connection to the
frame should be with bolts rather than by welding for the same reason.
Frame
20.
With the concept of the replaceable body proposed above,
t'nepurpose of the frame is to provide a strong supporting member
which maintains the axle, body and handles in the correct relative
positions. Steel tubing is probably the most suitable material for
this purpose, although a structurally sound arrangement can also be
achieved with angle iron. Some critical dimensions of the frame are
the overall
len&h as this affects manoeuvrability, I-aded weight
at the handles and ease of emptying; the width and height of the
hl_ndles,which must be tailored to the requirements of the operative;
and the attitude of the body when standing and when travelling, which
must be close to the horizontal in both conditions with sufficient
-lO-
ground clezrance when lifted. In proportioning the frame the
overall distribution of wei6 .t between the axle end the handles
is en important consideration. It is not desirable to carry 10096
of the load on the tie, and this is not feaeible with the singlewheel barrow layout in any case. A comfortable weight at the
handles aide the hauler in applying the necessery tractive
effort
to move and control the bsn*ow; however, an excessive weight at the
he&lee is counterproductive in these respects. In practice this
meane that for a western, single-wheel barrow the wheel should bs
placed as close to the body as a minimum working clearance will
al:o~~,whilst a two-wheel barrow should require en effort of about
lo-15 kg to lift the handles when loaded. IX ineufficient weight
is carried at the hendles, the momentum of the lc?d will tend to tip
the bexrow forwerd out of control when the whesl meets a slight
obetacle.
Western-Style Wheelbarrows
In considering pessible ways of organising earthmoving
21.
by wheelbarrow, it is useful to draw some parallels with
traditional operations such as haulage by headbasket. In these
traditional methods of working, a variety of gang organisations
have been observed. At the simplest level, a single worker excavates
and loads his own basket, and then hauls, unloads and returns, to
repeat this cycle independently of other workers. In practice this
method of working does not occur frequently, as it has the particular
disadvantage that the amount of load which can be transferred to the
head unaided is much less than that which can be comfortably carried
once the load is in position; outgut is therefore limited and the
method is restricted to those small-scale works having only one or
two workers where assistance at the pick-up-load stage would not
give sufficient increase in output to justify additional labor.
However, the same consideration does not necessarily apply to wheelbarrow working and it is quite feasible for an individual worker to
carry out the complete excavate/load/haul/unloadcycle, with good
results, provided the conditions of the work are not unduly arduous
inanyway.
Thus me 4 -heavy work can be performed with about 196of
theworkingdayae rest%Yf and given (say) no more than medium hard
soil and a mainly level haul, quite acceptable unit costs can be
achieved. If however the work is very heavy (say difficult excavation
and up-grade haulage) more than 5% rest could be required with
resulting low utilisation of tools and equipment. In these
circumstances alternative methods of working could probably give
better equipment utilisation whilst providing acceptable rest
periods for the workers.
The above description of individual working raises
22.
additional questions. If a group of labour is accustomed to
headbasket patterns of working, they may as a consequence shcw
considerable initial resistance to working one man per barrow,
this arrangement being contrary to their normal experience. A@-%
female workers often do not by custom carry out excavation, and in
India for example it is unlikely that pushing of wheelbarrows would
(5) This
75% excludes normal meal breaks, but it would include
essential rest defined as non-working time in Technical Memorandum
Ho. 8 of this series. In addition, the question of rest is discussed in more detail in Technical Memorandum No. 11 entitled
"A Literature Beview of the Ergonomics of Labour-IntensiveCivil
Construction".
-12-be acceptable to women in many areas. A further factor to the
problem is the possibility of increased skill to be gained by
specialisation in an activity, particularly excavation or loading,
or alternatively the possible benefit6 of each worker undertaking
a range of ac 'v'tiee in what might otherwise be a monotonous
work eetting kf .
Turning therefore to alternatives for the simple, one23.
man-per-barrow organisation, examples are found in the methods
observed during the study. What could be described as the second
level of organization involves two categories of worker, viz. the
excavator/loaderat the borrow pit digging the soil.and loading
the barrow, and the hauler who is hauling, unloading and returning.
Under most conditions using this arrangement it is fcund that
loading takes longer than the necessary rest period required by the
hauler, thus he waits longer for his barrow to be refilled than he
needs and unproductive time will result unless spare barrows are
used. The best productivity recorded to date was obtained from work
organised in this second-level manner and using spare wheelbarrows.
Quite rapid loading car be obtained at the next level of
24.
orgalisation involving three categories of worker, viz. excavators
loading into headbaskets, loaders transferring the soil from the
headbaskets to barrows and the barrow haulers themselves. Spare
baskets sre an alternative to spare barrovs.in this situation.
This typs of orgsnisation has been observed on canal construction
in Indonesia where it was particularly suitable because of mired
rock aud.soil caueing difficult excavation and losding conditions;
however, the possible drawback in this ' tance was seen to be tba
Y 7) with such a diversity of
difficulty of achieving good gang balance
individual activities comprising the task. In general, for sny
method more complicated than one-man-per-barror$
gang balance is a
critical factor.
It is hoped that the brief discussion above on orgsnisation
25.
of wheelbarrow working indicates that it is not possible to give
rigid rules, each situation must be Studied on its merit. In
introducing an unfamiliar piece of equipment attention to details
of the method of working in the paricular circumstances of the site
will generally prove to be very rewarding in terms of productivity,
but it is suggested that impznvementsto performance will take place
(6) It should be noted that in the industrialised countries the
whole question of work organisation, over-specialisationand worker
monotony is currently an urgent resesrch topic by behavior scientists
ad work+tUdy engineer.p,end there is nov a general movement towards
decreased specialisation.
(7)
The WeStiOn of gang balance is discussed in Technical Memorandum
No- 8 Of this series (see particularly para,15).
-lj-
over a fairly lengt,hyperiod if there is a significant deprture
from the equipment and/or organisation traditionally used.
Finally in this context a point whicilca? easily be
26.
overlooked is the importance of regular and careful maintenance
of wheelbarrows and barrow runs. A small but definite input here
will undoubtedly make all the difference between good and only
moderate results. Thus, for example, on a barrow run even a
small step or discontinuity can completely destrgthe momentum
of the barrow. T'neprinciple advantage of using barrows for haulage
is their ability to move a quite heavy load with ease, end it is
starting and stopping the barrow which consumes the most energy in
the 'hauler'scycle. Unnecessary interruptions to smooth running
are therefore most disadvantageous and should be treated as such,
emphasis on this being given in explaining the method to the workcan
force. In addition, under-inflated tires or stiff bear-6
significantly increase rolling resistance.
Chinese Wheelbarrows
Experience has not yet been gained during the study of
27.
methods of working wiih Chinese wheelbarrows. The higher load
ozpity and use of more than one hauler per barrow, or towing
by winch, snimal power, etc. (whichever may be appropriat8) will
require consideration in examining suitable orgauisation of the
work.
It is hoped to report on this subject in a revision ‘or
sqplement to this memorandum, in due course.
-14-
VI.
PRCDUCTIVITY OF wIXE!ZLBARROWS
The productivity data available and analyzed at the
28.
date of this memorandum comes from two sites in India and one
site in Uonrt?ia, where barrows were introduced for experimental or demonstration purposes. In India, wheelbarrow were
used ona paved surface to haul earth and rock to spoil $8),
cud for haulage in low embanlanentconstruction on a new road
project. In the low embankment work a 70 to 80 m haul on a
wood-plank barrow run was involved (see Fig. 1). Both the
Indian tasks were on essentially level hauls. In Indonesia the
wheelbarrows were used in irrigation canal construction on
sidelong ground. Haul length was mainly in the region of 20
to 30 m, predominantly on down gradients, but also including
someup-gradehaulage. Wood-plank barrow run6 were employed
here also. In total, the data represents some 50 days work,
with gang strengths of typically 4 to 10 men. In addition to
this data of actual construction work, the experience gained
from experimental studies with VhedbarrOWS in India and
Indonesia has been used in formulat:i.ng
the technical relationships given in the following paragraphs.
Fig. 6 shows the present interpretation of wheel29.
barrow productivity. This analysis of wheelbarrow ulag?
data has been carried out in terms of working time p"
g), with
data specially abstracted from the field observations. This
has been necessary, partly because of modified data abstraction
and processing methods developed during the study, but more
importantly, to exclude as far as possible the effects ofpoor gzz
balance and method-of-working differences between sites. In
this way the underlying characteristics of the haulage mode are
brought out more clearly. However, the productivity figures
thus derived represent 'good practice' on site, and must be
viewed aocordingly when compared with average productivities
from data covering the wide range of conditions and levels of
Neverefficient and inefficient working found in prs ti
thele6e: a wi,Jescatter of input ccefficients 77lo was &btained
from the analysis - typically showing lCQ6 variation for any
(8) For details of this work see Technical Memorandum No. 2 of this
series entitled, 'Increasing Output of Msnual Excavation by Work
Beorganisation: An Ebfsmpleof Passing Place Construction on a
Mountain Road'.
(9)
This working time (WT)is similar to that defined in Technical
Memorandum No. 9 of this series. Basically, it does not irl&lds an
dlowance of necessary rest or enforced waiting time.
(10) The inpu',coefficient 79
-. *he cqanttty o.fresource illPUt(e.g.
man-hours) per unit of work outpat (e.g. cubic-meter).
given h&l distance as represented by the diZference between Line A and
Line B in Fig. 6. It is believed that this range is mai,nlythe result of
difference0 that csn occur between high-incentive piecework payment at
the more productive level and daily-paid work at the less productive
level. Other, unidentifiable site-dependent factors also contribute to
the range of values found however, and a statistical basis for the effect
of payment method has not yet been fully established.
The method of analysis used to produce Fig. 6 approached the
30.
deteTmin4.tionof productivity by a twofold path. Firstly, extensive
records of the work-element values measured in the field were used to
establish theox??ticalcycle times. The cycles being calculated for the
case where no tit-while-loading occurs, as would be obtained with correct
gang balancing and sufficient spare wheelbarrows. Upper and lower bounds
of the work-element vslues were selected, to reflect the differences
observed between sites. A simple mathematical model of the work cycle was
then used to genente a technical relationship between input coefficient
and haul lengtii. The basic elements of this model are given below in
Table 3 and in the formula for Line A and Line B.
Table 3
: 'Cpperand lower cycle elements for wheelbarrow haulage
(see also Fig. 6).
Cycle Element in
Working Time
Payload
Site Manauement Conditions
Line A: Good Orgsnisation Line B : Fair Orgsnisation
High Incentive
Non-incentive
100 kg
8O3n/&n.
Pick-up Load Tiqe
unlo
ime
Rest"c"T
11
75
0.1
0.25
0.5
m/min.
min.
min.
min.
70 k@;
50 m/&n.
40 m/min.
0.2 mul.
0.3 min.
1.1 min.
The hauler input coefficient is therefore given as:
LIKE A i%Il-;?our
(WT)/m3 = 0.25 +
LIE B Man-hour (Wr)/m3 = 0.67 +
where H = Haul length in meters.
0.0076H
0.019H
(111 It is interesting to note that the speed empty is usually less than
the speed xU1 and undoubtedly the hauler gets some essential rest while
walking back to the loading point. However, rest will be taken at other
points in the cycle and it is not necessarily obvious when this rest
occura; the conrmonestpoint is usually at the borrow area immediately
prior to tw
up a refilled barrow.
,
- 16 Secondly, an analytical approach was used to abstract from
31.
the field data the observed resource inputs and total outputs for each
available group of observations. In doing this, the time spent by
haulers naiting-while-loadingwas excluded, unless it was very small.
Necessary rest and all other essential working time was included.
In using Fig. 6 it should be noted that Line A and Line B
32.
give -haulageproductivity on the basis of the simple cyclical load-haulunlosd-returnmodesl. The resource input considered is the hauler's
working the, and therefore includes the time elements for taking up the
loaded bsrrcw, hauling loaded, uriLoading,returning empty, and necessary
rest (irrespectiveof where it occurs in the cycle). Also, the haul
distance in meters assumes a more-or-less level haul route as no accurate
relationship has et been determined to enable the equivalent hauJ.leg&h
to be caktiated( 92). However, initial consideration of this subject
suggests that each meter rise will effectively add 10 - 2C meters to
the haul 1ength;thu.a a'haul of8Omwithatotal
rise of @wouldhave
an
equivalent haul length of about 14Cm (i.e. 80 + 4 x 15).
(Q
e method of calculating equivalent haul length for headbasket
haulage is discussed in Chapter V of Technical &norsndum No. 12 of
this series; the approaoh for wheelbarrows will be similar, but it is
not to be expected (necessarily) that the same equivalence factor will
he appropriate.
-
vi.
77
&,
-
~0s~ OF wREEM%UOW
FiAiJidGE
If it is first verified by observation that for a particular
33*
site the resxlts given in Fig. 6 are applicable to that site, then it is
possible to derive unit costs for wheelbarrow haulage. An illustrative
exsntpleis given below;
Firstly, as tne results have been expressed in terns of
34.
WOEKI?fGTEE an estiaator concerned with daily or weekly production must
first decide what the achwl average daily wcrking time and daily wage
of labor will be. I3 this matter it is suggested that the values given
in Table 4 might represent Itypical values for Line A and Line B
situations.
Table 4
:
Suggested (and illustrative) values of available time03) ,
working time and daily wage.
Available time per day
R?tio WT/Z!T
Working t&e per day
&ily wage for labor *
10 hours
Yoo/o
yhours
TJ.s.$1.2
8hcum
75%
6 hours
u.s.s 0.5
* The tan 'dailywage rates I for the incentive method of payment is merely
a n&ion&l concept as the actual wages paid are based on the oui@ut. For
incentive method of payment, it in raLl.ityreflects the daily earning of a
waker.
Secondly, the mean haul length for the work must be assessed - let
3.5.
The c;ilcula%on shozL9 be -5.n
29 999ume fbzec velws 0-P25,7X3and 1Xk (:!o',e:
t,em.sof e@vaLent hanl lenpth to allw f-he
effect of rise, hut *hi.cannot be done until an accurate equivalency factor has been determined, as
The likely range of outguts and costs can now be
discussed in para. 32).
cakulatad as given in Table 5 and plotted in Pig. 7.
(13)3'ordefinition of
of this series.
Available Time (AT) see Technical Memorsndum No. 8
- 16 -
of output and costs for wheelbarrow haulage.
Table 5 : Yiiarye
Ehll
Length
(4
I
25
50
100
I
25
50
100
Input coefficient
(~mm Fig. 6)
Output per man-dey
o tbrking
time 3er dq
Iuput coefficient
Cost per unit of
Daily wage plus
Site Management Condition
LineA
LineB
6.44
0.63
1.15
1.01
2.57
20.5
14*3
6.9
1.62
5-2
3.7
2=3
U.S.!!
per
In3
As dcated
in Table 5, in calculating the unit cost of output it
36.
is necessary to add to the wage of the hauler his portion of the cost of
cost will
equipment, including the cost of any barrow runs. This equi~nt
not be a constant and generslly haa to be averaged over a working season. It
also depends on a number of factors such as the size of gang, the mxnber
of apare berrows and the haul length. However, typically for a I&w A
situation the equipment will cost between U.S. $ 0.2 - 0.6 per dsy per beXi!er,
value has been used in Table
with
an averae;e value of U.S. $ 0.4. This avem
Similarly,
for
a
Line
B
situation
equipment
cost
is likely to be between
5*
U.S. 8 0.15 - 0.45 per dsg per hauler, with sn average of U.S. $ 0.3. In team
of wage rates this means that on average for Line A situations the equipment
is 33% of the hauled8 vage or 25% of the total cost of haulage. The
corresponding values for Line B situations are 6046and 37%.
it must be stressed that the unit costs given in Table 5 refer to
37.
the haulage only and they do&
includer-
(&;’ costs of other activities in the task (e.g. excavation and
l=d.wid i
(b)
e . espervision
. and overhead
. costs;
(c) profits (if appropriate).
and
- 15 -
Vii.
DISCUSSLO?U'
Various traditional labor-intensive haulags modes such as the
23.
double yoke, the head basket, different beasts of burden, and animaldrawn carts are fcund on earthworks projects in India and Is'ldonesia.
In addition the diesel truck, loaded and unloaded manually, is a common
mode of haulage. At their best and with the current wag rates in those
countries (i.e. U.S. $ 0.5 per day for daily paid labcr), such operations
yield costs believed to be on a par with, or lower than, equipmentintensive costs in similar circumstances. When operated efficiently, as
is often the case where small contractors are working, these existing
mcdes show a quite &finite pattern of application. IA thd pattern, a
?rinci@ factor is hsul length. Thus, manual load sarrying is the most
coqetitive method on short hauls, for short to medium tistences the beast
of burden is used, fcr medium hauls the animal cm,
and finally on long
hauls the truck gives the lowest unit cost. On examination of this pattern
iT is seen that the size of the load carried in each mode of haulage
correlates well with the appropriate haulage distance, as ehown in Table
6.
Table 6
: Correlation between haulage method, typical load carried znd
preferred haul distance.
Haulage Method
B-Y
CEiWl
~WeCsrt,OxCart
Truck
PreferredHaul
500 and upwards
It is not proposed to discuss in this memorandum the explanation
39.
of this pattern, rather to say that the wheelbarrow, or any other
of alternative modes is available. It is considered that in the Indian and
Indonesian context, the wheelbarrow appears to be an appropriate mode for
hauldistances of about 50 to 150 m, and is a viable alternative to
headbasket and donkey haulage. Indeed, the productivity data,analysed so
far suggests that at an optimum haul distance approaching lOOm, where steep
gradients sre not involved, the western-style barrow can give results
superior to either headbaskets, donkey haulageL or equipment-intensive
methods.
- 20 -
40.
However, it must be stressed that in an environment
different from that of India-the applications for wheelbarrows
could well be different. It,seems for example that in some
regions of China the wheelbarrow is used very extensively in
earthmoving work, over haul lengths up to nearly 1 km. It is
possible to speculate that the occurrence of one predominant
mode of labor -intensive haulage may be due to a very different
relative cost and availability of human and animal labcr in
the different conditions there. Similarly it may be suggested
that in some African countries, where perhaps pack animals are
scarce and no tradition of construction work is found, intro$&ion
of wheelbarrows would be more acceptable than the
headbasket or yoke, whilst to introduce a suitable beast of
burden may not be feasible.
Some of the data upon which the analysis presented in
41.
this memorandum is based has been obtained from work conducted
on an experimentai basis. It thus occurs that factors not present
when on-going traditional works are observed can influence the
results obtained. The two main effects are those of an insufficient
learning period available when workers are introduced to new
techniques and of the rather higher supervision level,which is
difficult to avoid. Possibly however, these factors may tend to
compensate rather than being additive in effect. Amongst the objects
of studies still continuing is to gather data
of the program
where greater familiarity with new methods and a more.normal
supervision input exist by virtue of a longer period of work in a
given experimental area. Greater confidence will thus be obtained
in making comparisona with traditional methods.
Future revisiona of thzi.3
memorandum will, it is hoped,
42.
benefit from the additional data and expand the coverage of the
topic by considering more fully alternative methods of working and
wheelbarrows based on the Chinese pattern. The results of
institutionalisedresearch on fundamentals such as the scil-wheel
interaction ehould also be available.
Figure 1.
WESTEZX-STYLE BARROW DEVELOPED FOR STUDIES OF
L3W EK!&UUKM!JNTCONSTRUCTION IN INIXA
(Weight 26kg Payload !.OOkg)
Figure 2.
'VIES--SW
BARROW, LOCALLY AVAILABLE IN
lIKfXWSIA, I%ED IN CANAL CONSTRUCTION STIJDES
(Weight 16kg Payload 75kg)
Figure 3.
Figure 4.
EAULAlE ONUP-GRADEUSINGWESTERN-STYLE
AhJTI.KEii3RBARROWRU-N
(Weight 16kg Payload 75kg)
WREELBARROW
CHLNESE WHEELBARROW IN USE ON FLOOD PREVEICION
WORKS IN NORTHERN CHYKNA
(Weight Approx 50kg Payload Approx 200kg)
Hard
Smooth
Cr.0
SurfoCP
05
Loose
soQndGrOVCl
crm0 3
NOTE .-
C; - Cceltlec oen I al
rollmg resistance
Exper~menlai
Result
Hard Earth Surface
( Earrow
t Load I Wight.
kg.
an
Wheelbarrow
Pick-up
haulage
Load
- Haul
activity
Full
consists
-Unload
of :
- Haul
The
figures given below assume good
waiting -while - loading time ,other than
Empty
gang balance and include
essential
rest .
Eauations
LINE A
LINE 9
I.C. = 0.25 + 0.0076 H
i.C. = 0.67 + O-0186 H
H in
a!c!!4
LINE A
LINE8
O-85 + 0.0267 H
l*60+ 0.0444 H
minutes
minutes
Times
NO
meters
H in meters
3-o =
?I
*
5
k
ROUTE CONDITION: GOOD ( BARROW - RUNI
o-s-
07
0
20
H=HAUL
1
il
NotesA
40
LENGTH
(m1
I
60
(see note
I
80
100
#120
4.1
Volw1.5of output measured in-situ at borrow area.
Calculationsassume in-situ soil density of 1.75 tonne/d.
(f) Outputs apnlicableto hauler with average body weight of 55 kg.
(4) Applicable-formore-or-lesslevel hauLage (see para. 32), haul
length is distancefrom the pick-up point to the unloadingpoint.
Figure 6. mow
HAmGE
: PRODUCTIVITY/EtAULLENGTHRELATIONSHIP
Wheelbarrows
0*5
M---e
/
LINE
0
0
Headbaskets
/
0
0
/
/
/
/
/
/
LINE
.B
LINE
A
LINE
B
)II
!ii
0 0
0
HAUL
Notes:
25
50
75
100
LENGTH’ 31(ml
(1) Graphs for wheelbarrows prepared on basis of Table 5.
(2) Graph for headbaskets taken from Technics3 Memorandum No.
12 of this series, with minor coxzections for soil density
differences.
(3) This should be regarded as the equivalent haul length
(see paza. 32).
(4)
See notes (1) & (3) of Fig. 6.
Figure 7, UNIT COST OF WEEELT~ARROWHMZAGE FOR D~TEREXP JUUL LENGTHS
~OMPAItED~S~LARHEADEAsKcpHAULAGE.
Copies of Oker
&&xrX.&
in this SeriC?sjViT!l tile latest I"evi3j.~~i:‘~
* may be obtained from:
where applicabie) 2~"~r.ti.v;cua;
revislors
iirozlTzojccts Tkzpartizent,
Transportsticn a.;:!
International Rank for Reconstruction and Development,
1613 IiStreet N.W.,
d.
Washington D.C. 204jj,
United States of America.
Technical &mora.nda published in this series to date are as folio:.::::
Rmber
1
2
3
Title
Dated
Comparison of Alternative Dzsig
Wheelbarrows for ilaulagein Civil
Construction Tas!:s
.Jcm’75
Increasing Output of l%ziaal
Excavation by Work Reor~anisation
An example of Pzxsing Place
Construction on 8 ~lountainRoad
Jmr75
Comparison of Different fiiodcs
of
Haulage in Za.rtll!rorks
Jan’75
4
Effect of Health and Nutrition
Status of Road Construction Workers
in Northern India on Productivity
Jan’75
5
Comparison of Hand Laid and
Machine LaidRoad Surface
J?ebI
75
Haulage with lift of Materials
Lifting Sand by Ropeway
Feb I75.
G
7
8
9
10
11
.-- Revision::
Supplament
Productivity Rates of Earthmoving
Ihchines
May’75
Collection of Productivity Data
from Civil Construction Projects
JULY'75
Report of First Road
Demonstra'tionProject
c
Augusff75
A System of Deriving Rental Charges
August'75
for Construction Equipment
A Literature Review of the Ergonomics
of Labor-Intensive Civil Construction August '75
I
--
Xwnber
Title
Dated
Revisions
--
12
Haulageby Hsadbaskets,Shoulder
Yokes and ot!mr Manual Load
October '75
CarryingMethods
The .t,ise
of hheeibarrowsin
Civil Construction
October ‘75
HardwareResearchSummary
October ‘75